The invention discloses a whitening effect judging method based on spectral imaging. The whitening effect judging method comprises the following steps: (a), acquiring a standard spectral curve; (b), acquiring the spectral feature curves of skin before and after whitening; (c), carrying out spectral analysis. The method is formed by perfectly combining a spectral imaging technology and a spectral analysis technology, and the spectral reflectivity curves of different positions of the skin can be obtained by the spectral imaging and analysis technology. As the spectral reflectivity curves of the pigment-free skin of different people in a waveband range of 450-650nm are basically consistent, the spectral reflectivity curve can be used as the standard spectral curve. The whitening effect is quantitatively evaluated through comparing the similarity of the spectral feature curves of skin before and after whitening and the standard spectral curve, the problems of uncertainty and slow evaluating speed of the existing whitening effect evaluating method depending on subjective consciousness are solved, and the purpose of rapidly obtaining the whitening effect is achieved.